Cancer mortality in women after repeated fluoroscopic examinations of the chest.

Among 1,047 women fluoroscopically examined in average of 102 times during pneumothorax therapy for tuberculosis and followed up to 45 years (average = 27 yr), no increase in the total number of cancer deaths occurred when these women were compared to 717 women who received other treatments [relative risk (RR) = 0.8]. However, elevated risks of mortality from stomach cancer (RR = 2.3), rectal cancer (RR = 3.8), breast cancer (RR = 1.2), lung cancer (RR = 1.8), and leukemia (RR = 1.2) were observed, but none was statistically significant and all were based on very small numbers of deaths. These increases were balanced by decreases of genital cancer (RR = 0.2), pancreatic cancer (RR = 0.9), lymphoma (RR = 0.6), and all other cancers (RR = 0.1). Average cumulative absorbed doses were 110 rads for the lungs, 33 rads for the trunk, 13 rads for the active bone marrow, and 7 rads for the stomach. The following upper levels of excess risk could be excluded with 95% confidence: 3.5 deaths/10(6) woman-year (WY)-rad for lung cancer, 4.8 deaths/10(6) WY-rad for lymphoma, and 12 deaths/10(6) WY-rad for leukemia. These findings indicated that the carcinogenic effect of multiple low-dose X-ray exposures was not greater than that currently assumed.